#!/usr/bin/python3
import teacher

class grade:
    """A Grade class"""
    def __init__(self, id ):
        self._id = id
        self._classrooms = {}
 
    @property
    def id(self): return self._id
    
    @property
    def classrooms(self): return self._classrooms
    
    def add_classroom(self, new_classroom):
        if(not self._classrooms.get(new_classroom.id)):
            self._classrooms.__setitem__(new_classroom.id, new_classroom )

    def __repr__(self): 
        return repr(self.id)
        
        
def main():
 
    pass

if __name__ == "__main__": main()        